Definition extracted with permission from Simon, Fritz, et al, Family Process, Inc.: Language of Family Therapy: A Systemic Vocabulary and Source Book (Family Process Press Series)
"Feedback is a method of controlling a system by reinserting into it the results of its past performance" (Wiener, 1954/1967, p. 84). Feedback loops and feedback structures are essential elements in cybernetic systems. In traditional family theory, negative (deviation-counteracting) feedback was conceptualized as regulating families and other systems (homeostasis), as a precondition for the survival of the system in a constantly changing environment. This formulation was more satisfactory for explaining stability and morphostasis than in understanding change, especially discontinuous change. The concepts of positive (deviation-amplifying) feedback and evolutionary feedback, as well as morphogenesis, coherence, and coevolution, have been advanced to correct "simple" feedback theories.